A hypothetical plant species, flower color is determined by the following bioche

Question

A hypothetical plant species, flower color is determined by the following biochemical pathway: Genes A, B, C, D and I are independently assorting. The dominant alleles, A, B, C, and D, encode active enzymes that catalyze the corresponding reactions, and the recessive alleles, a, b, c, and d are nonfunctional. The dominant I allele totally inhibits the action of gene C, while i has no effect. a. A cross is made between AAbbCCDDII and AABBCCDDii plants.

The genotype of the F1 plants are: AABbCCDDIi.

These F1 plants are self-crossed. What is the phenotypic ratio of the resultant F2 generation?

Explanation / Answer

Answer:

AABbCCDDIi X AABbCCDDIi

Gametes: ABCDI, AbCDI, ABCDi, AbCDi

F2 population: AABbCCDDII= Orange since dominant I allele inhibits C allele enzyme and hence there no progression of the reaction from C to D pathway.

AABBCCDDIi= Orange since dominant I allele inhibits C allele enzyme and hence there no progression of the reaction from C to D pathway.

AABbCCDDIi= Orange since dominant I allele inhibits C allele enzyme and hence there no progression of the reaction from C to D pathway. (this type of genotype appears twice)

AAbbCCDDIi= Yellow since dominant I allele inhibits C allele enzyme and hence there no progression of the reaction from C to D pathway and also recessive b allele does not allow the reaction from B to C to D.

AABbCCDDii= Purple since the recessive 'i' allele has no effect on the pathway, the reaction proceeds from A to B to C to D and there is purple color formation

Therefore phenotypic ratio= 4Orange: 1Yellow: 1Purple

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